High Resolution Heat Transfer Measurements on the Stator Endwall of an Axial Turbine

Abstract

In order to continue increasing the efficiency of gas turbines, an important effort is made on the thermal management of the turbine stage. In particular, understanding and accurately estimating the thermal loads in a vane passage is of primary interest to engine designers looking to optimize the cooling requirements and ensure the integrity of the components. This paper focuses on the measurement of endwall heat transfer in a vane passage with a three-dimensional (3D) airfoil shape and cylindrical endwalls. It also presents a comparison with predictions performed using an in-house developed Reynolds-Averaged Navier–Stokes (RANS) solver featuring a specific treatment of the numerical smoothing using a flow adaptive scheme. The measurements have been performed in a steady state axial turbine facility on a novel platform developed for heat transfer measurements and integrated to the nozzle guide vane (NGV) row of the turbine. A quasi-isothermal boundary condition is used to obtain both the heat transfer coefficient and the adiabatic wall temperature within a single measurement day. The surface temperature is measured using infrared thermography through small view ports. The infrared camera is mounted on a robot arm with six degrees of freedom to provide high resolution surface temperature and a full coverage of the vane passage. The paper presents results from experiments with two different flow conditions obtained by varying the mass flow through the turbine: measurements at the design point (ReCax=7.2×105) and at a reduced mass flow rate (ReCax=5.2×105). The heat transfer quantities, namely the heat transfer coefficient and the adiabatic wall temperature, are derived from measurements at 14 different isothermal temperatures. The experimental data are supplemented with numerical predictions that are deduced from a set of adiabatic and diabatic simulations. In addition, the predicted flow field in the passage is used to highlight the link between the heat transfer patterns measured and the vortical structures present in the passage.

Purge flow effects on rotor hub endwall heat transfer with extended endwall contouring into the disk cavity

“…Heat transfer measurements in the facility were performed with an infrared based technique described by (Lazzi Gazzini et al, 2017b) and (Laveau et al, 2014). A Flir IR SC7300L camera was used to record the temperature of the rotor endwall through infrared transparent Zinc-Selenide (ZnSe) windows installed in the rotor casing ( Figure 2).…”

Effect of Tip Clearance on Flow Field and Heat Transfer Characteristics in a Large Meridional Expansion Turbine

“…Friedrich et al [29] of the German Aerospace Center carried out detailed experiments on the EGG transonic planar cascade, indicating that the separation of the HV ps started from a 40% axial chord length and was attached to 80% of the axial chord length. Similarly, in the study of Benoit Laveau et al [30], an experimental analysis of the turbine guide vane was conducted, and it was concluded that the HV ps separated from 30% axial chord length and attached to 75% of the axial chord length. Compared with non-expansion blades, the separation and attachment point of horseshoe vortex pressure surface had an advance of 15%.…”

A computational investigation of the effect of surface roughness on heat transfer on the stator endwall of an axial turbine

“…The stationary rows consist of 36 vanes and the rotor is composed of 54 blades. More details of the experimental facility are presented by Behr et al 15 Recently, Laveau et al 16 installed and demonstrated the use of a heat transfer measurement platform in the first stationary row of the turbine in the LISA facility. Measurements of heat transfer quantities, namely the heat transfer coefficient and the adiabatic wall temperature, were performed using a specially developed measurement platform, providing a quasi-isothermal boundary condition.…”

“…Inlet profiles for total pressure, total temperature and turbulence intensity were obtained from corresponding experiments. 16 The corresponding turbulence length scale profile was determined in a separate CFD study for the inlet region of the test facility. Table 2 provides a summary of the range of the investigated boundary conditions.…”